import math

[x1, y1, x2, y2] = [float(x) for x in raw_input().split()]
print(math.sqrt((x2 - x1) ** 2.0 + (y2 - y1) ** 2.0)) import math math float(x) for x in raw_input().split() for x in raw_input().split() x raw_input().split() ().split () raw_input split for x in raw_input().split() float(x) float x [x1, y1, x2, y2] = [float(x) for x in raw_input().split()] [x1, y1, x2, y2] x1 y1 x2 y2 [float(x) for x in raw_input().split()] print(math.sqrt((x2 - x1) ** 2.0 + (y2 - y1) ** 2.0)) print math.sqrt((x2 - x1) ** 2.0 + (y2 - y1) ** 2.0) math.sqrt math sqrt (x2 - x1) ** 2.0 + (y2 - y1) ** 2.0 (x2 - x1) ** 2.0 x2 - x1 x2 x1 2.0 (y2 - y1) ** 2.0 y2 - y1 y2 y1 2.0
import math

[x1, y1, x2, y2] = [float(x) for x in raw_input().split()]
print(math.sqrt((x2 - x1) ** 2.0 + (y2 - y1) ** 2.0))